NOTE: This disposition is nonprecedential.

United States Court of Appeals 

for the Federal Circuit ______________________

ALACRITECH, INC.,

Appellant

v.

INTEL CORPORATION, CAVIUM, LLC, DELL INC.,

Appellees

UNITED STATES,

Intervenor

______________________

2019-1464

______________________

Appeal from the United States Patent and Trademark 

Office, Patent Trial and Appeal Board in Nos. IPR2017-

01393, IPR2017-01714, IPR2018-00374.

______________________

Decided: July 16, 2020

______________________

SANFORD IAN WEISBURST, Quinn Emanuel Urquhart & 

Sullivan, LLP, New York, NY, for appellant. Also represented by JOSEPH M. PAUNOVICH, Los Angeles, CA. 

 GARLAND STEPHENS, Weil, Gotshal & Manges LLP, 

Houston, TX, for appellee Intel Corporation. Also represented by MELISSA LARUE HOTZE; GREGORY SILBERT, New 

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2 ALACRITECH, INC. v. INTEL CORP.

York, NY; AMANDA BRANCH, ANNE MARIE CAPPELLA, Redwood Shores, CA. 

 KARINEH KHACHATOURIAN, Rimon, P.C., Palo Alto, CA, 

for appellee Cavium, LLC. Also represented by NIKOLAUS 

A. WOLOSZCZUK. 

 KIRK T. BRADLEY, Alston & Bird LLP, Charlotte, NC, 

for appellee Dell Inc. Also represented by EMILY CHAMBERS 

WELCH, Atlanta, GA; BRADY COX, Dallas, TX. 

 MELISSA N. PATTERSON, Appellate Staff, Civil Division,

United States Department of Justice, Washington, DC, for 

intervenor. Also represented by ETHAN P. DAVIS,

COURTNEY DIXON, SCOTT R. MCINTOSH; THOMAS W.

KRAUSE, FARHEENA YASMEEN RASHEED, Office of the Solicitor, United States Patent and Trademark Office, Alexandria, VA. 

 ______________________

Before MOORE, CHEN, and STOLL, Circuit Judges.

CHEN, Circuit Judge.

Alacritech appeals from the final written decisions of 

the Patent Trial and Appeal Board (the Board) in the 

above-captioned inter partes review (IPR) proceedings 

holding claims 1, 6, 9, 12, and 15 of U.S. Patent No. 

9,055,104 invalid as obvious.1 We affirm. 

1 Alacritech’s appeal briefing included a challenge to 

the appointment of the administrative patent judges on the 

Board under the Appointments Clause of the Constitution, 

but this challenge has since been withdrawn and waived. 

See Dkt. No. 70. 

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BACKGROUND

The ’104 patent relates to network communications, 

and in particular to the use of a network interface device to 

offload network processing tasks from the central processing unit (CPU) of a host computer. ’104 patent at Abstract. To transmit data to the network, the computer 

supplies a command along with the data to the network interface, which in turn processes and transmits that data 

according to the Transmission Control Protocol (TCP) before indicating to the computer that the data has been 

transmitted. Id. at col. 3 ll. 37–47. TCP also requires the 

recipient of the data to respond with acknowledgments

(ACKs) indicating to the transmitting device—here, the 

network interface—which data has been successfully received. Id. at col. 2 ll. 10–15. The claimed invention specifies that the network interface indicates to the 

transmitting computer that the data has been transmitted 

“prior to receiving” the ACK for all of the transmitted data. 

Claim 1 is representative:

1. A method for communication involving a computer, a network, and a network interface device of 

the computer, the network interface device being 

coupled to the network, the method comprising:

receiving, by the network interface device from the 

computer, a command to transmit application data 

from the computer to the network;

sending, by the network interface device to the network, data corresponding to the command, including prepending a transport layer header to at least 

some of the data;

sending, by the network interface device to the computer, a response to the command indicating that 

the data has been sent from the network interface 

device to the network, prior to receiving, by the network interface device from the network, an 

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acknowledgement (ACK) that all the data corresponding to the command has been received; and

maintaining, by the network interface device, a 

Transport Control Protocol (TCP) connection that 

the command, the data and the ACK correspond to.

Id. at claim 1 (emphasis added).

The Board found all of the challenged claims unpatentable over U.S. Patent No. 5,937,169 (Connery) in view of 

the knowledge of a skilled artisan and, in the alternative, 

over Connery in view of PCT Patent Publication No. 

WO 00/13091. Relevant to this appeal, the Board found 

that Connery discloses the limitation of “sending, by the 

network interface device to the computer, a response to the 

command indicating that the data has been sent from the 

network interface device to the network,” and that Connery’s network interface sends this response “prior to receiving . . . an acknowledgment (ACK) that all the data 

corresponding to the command has been received.” J.A. 

19–25; ’104 patent at claim 1.

Alacritech appeals, and we have jurisdiction under 

28 U.S.C. § 1295(a)(4)(A). 

DISCUSSION

Obviousness “is a question of law based on underlying 

findings of fact.” In re Gartside, 203 F.3d 1305, 1316 (Fed. 

Cir. 2000) (citation omitted). We review the Board’s findings regarding the scope and content of the prior art for 

substantial evidence. Rambus Inc. v. Rea, 731 F.3d 1248, 

1251–52 (Fed. Cir. 2013).

The sole dispute in this appeal relates to what Connery 

discloses, and specifically, the relative timing between a 

particular “interrupt” message sent from Connery’s network interface to the computer’s central processing unit 

(CPU) and the receipt of an ACK sent from a computer that 

received the transmitted data. 

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Like the ’104 patent, Connery discloses that network 

protocol processing can be offloaded from the CPU to a network interface. Connery at col. 1 ll. 7–11. As Connery explains, higher layer network protocols such as TCP were 

typically “handled by software drivers” and “a protocol 

stack executed in the host processor,” i.e., CPU. Id. at col. 

1 ll. 20–21, 31–33. To transmit data according to TCP, the 

CPU would first package that data into “appropriately 

sized segments.” Id. at col. 1 ll. 37–41. Separately, the 

CPU would also monitor acknowledgment (ACK) messages 

from the recipient to ensure, for reliability purposes, that 

“the amount of data sent onto the network” “does not exceed” the advertised receiving capacity of the recipient. Id. 

at col. 1 l. 56–col. 2 l. 13. To reduce the load on the CPU, 

Connery explains that segmentation of data for transmission can be offloaded from the CPU to the network interface. Id. at col. 7 ll. 47–49, 60–64. With the exception of 

data segmentation, Connery’s CPU continues to handle the 

remaining aspects of the TCP protocol. Id. at col. 5 ll. 51–

53, col. 6 ll. 15–18. 

Connery’s network interface accepts a command from 

the CPU to transmit a “large datagram” and divides that 

datagram into individually transmitted segments according to the TCP network protocol. Id. at col. 2 ll. 46–57. 

Once the network interface transmits the data segments of 

the large datagram, Connery discloses that the network interface can send a single interrupt to the CPU. Id. at col. 

7 ll. 60–63. The parties dispute whether this interrupt sent 

by the network interface occurs before, or after, the network interface receives an ACK indicating that all of the

transmitted data was successfully received by a destination computer. 

The Board agreed with the petitioner that a skilled artisan would understand Connery’s single interrupt per 

large datagram as indicating that “all generated packets 

from the large datagram have been sent from the network 

interface to the network regardless of whether any 

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corresponding ACK[s] have been received.” J.A. 23. The 

Board further found that Connery’s interrupt would be 

generated by the network interface prior to receiving an 

ACK from the recipient for all of the transmitted data. 

Substantial evidence supports the Board’s fact findings. 

The Board reasonably found that the interrupt generated by Connery’s network interface is strictly associated 

with the task given to the network interface—transmitting 

data in segments—and not other tasks, such as ACK processing, that the host computer has not offloaded to the network interface. As Intel’s expert, Dr. Horst, explained, 

such an interrupt to indicate that the network interface is 

done with segmenting and transmitting data “is needed because otherwise the host would not know when the [network interface] hardware is free to accept the next large 

packet to be sent.” J.A. 1670. In contrast, the Board found 

that ACK processing is “unaffected by Connery’s alleged 

improvements to segmenting and transmitting data” on 

the network interface. J.A. 23. Thus, “an ordinarily skilled

artisan would have presumed ACKs are processed in the 

normal processing of a TCP/IP protocol stack operable in 

the host computer.” Id. In other words, while Connery contemplates offloading the task of transmitting data in segments from the CPU to its network interface, which in turn 

sends an interrupt back to the host when that task is complete, ACK processing is not affected; the ACK, as a separate message, continues to be sent from the recipient and 

handled by the CPU in a conventional manner. Because 

ACK processing has not been offloaded from Connery’s

CPU to its network interface, the Board fairly concluded 

that the “interrupt” generated by the network interface indicates that the interface has completed its data transmission assignment rather than referring to the ACK. Thus, 

like the Board, we are not persuaded by Alacritech’s argument that Connery’s interrupt must include the ACK or depend on receipt of the ACK. 

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After determining that Connery’s “interrupt for transmit complete” is sent by the network interface to the CPU

independently of the receipt of any ACK, the Board considered the relative timing between the transmit complete interrupt and the return of ACKs for all of the transmitted 

data. J.A. 24. We see no error in the Board’s reasoning 

that “an interrupt for transmit complete would precede” 

the ACK indicating that all data segments of the datagram

have been transmitted “because there is substantial latency in receipt of the ACK as compared to” the interrupt. 

Id. After the network interface “transmit[s] the last packet 

of the datagram,” the transmit complete interrupt would 

be “sent immediately” and “virtually instantaneous” between the network interface and the CPU, whereas there 

would be “substantial latency,” i.e., delay, from the transmission of the last packet of the datagram over the network, the processing of that packet at the receiving 

computer, and the return transmission of an ACK for that 

packet from the receiving computer to the transmitting 

network interface. Id. 

Alacritech alleges that, under the Board’s reading, 

Connery’s network interface must also generate a second 

interrupt “to let the CPU know that the ACKs have been 

received and the data transfer is complete,” rendering the 

initial transmit complete interrupt “meaningless.” Appellant’s Br. at 20–22. According to Alacritech, the CPU must 

wait for this alleged second interrupt indicating receipt of 

the ACKs for the first batch of data before “sending the 

next batch of data to the [network interface] for transmission.” Id. We note that Alacritech did not make this “second interrupt” argument before the Board, and arguments 

not made below are generally waived. In re NuVasive, Inc., 

842 F.3d 1376, 1380 (Fed. Cir. 2016) (“a party waives an 

argument that it ‘failed to present to the [PTAB]’ because 

it deprives the court of ‘the benefit of the [PTAB]’s informed 

judgment’”) (citing In re Watts, 354 F.3d 1362, 1367–68

(Fed. Cir. 2004)). Although Alacritech points out that it 

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argued to the Board that a skilled artisan would not depart 

from the allegedly “conventional” practice in which “the 

network interface device waits for an ACK for all the transmitted data before it sends a response indicating the command has been completed to the local host,” that says 

nothing about a second interrupt in addition to Connery’s 

or that Connery’s CPU must wait for a second interrupt 

before supplying additional data to its network interface 

for transmission. Appellant’s Reply Br. at 1–2 (citing J.A. 

444). To the extent that Alacritech argued that Connery’s 

interrupt is dependent on the receipt of an ACK, we explained above that substantial evidence supports the 

Board’s conclusion that Connery’s interrupt is indicative of 

transmit completion rather than ACK receipt. 

In any event, nothing in Connery or the record suggests 

that Connery’s CPU must wait for ACK confirmation before supplying additional data to the network interface for 

transmission. Alacritech does not contend that the TCP 

protocol itself imposes such a requirement on the interaction between the CPU and the network interface. Appellant’s Reply Br. at 8–9 (acknowledging that TCP’s flow 

control mechanism, which includes ACKs, “does not specify 

the communications between the sending computer’s CPU 

and a [network interface card]”). As both parties agree, the 

TCP protocol controls the flow of data between transmitting and receiving devices based on a “window” advertised 

by the receiving device. The receiving window defines how 

much data the transmitting device can send to the receiving device without waiting for ACKs from the receiving device. Connery itself explains that the sending computer 

can continue to transmit data without waiting for any 

ACKs so long as the “sender controls the amount of data 

sent onto the network so that it does not exceed the size of 

the advertised window of the destination.” Connery at col. 

2 ll. 3–13. Connery further confirms that, consistent with 

TCP’s constraints on transmitting data, the CPU can

“send[] a plurality of datagrams to the network interface 

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ALACRITECH, INC. v. INTEL CORP. 9

for the same session,” and the network interface will “concatenate[],” i.e., link, “data from the current datagram”

that is sequentially aligned “with data from the following 

datagram.” Id. at col. 4 ll. 34–41. As Intel explains, such 

concatenation between datagrams would be impossible if, 

as Alacritech urges, the following datagram was not made 

available to the network interface until after the current 

datagram is transmitted and an ACK received.

In sum, the Board’s decision finding that Connery’s interrupt represents the network interface’s completion of 

transmission of a large datagram and occurs prior to the 

receipt of an ACK for all of the data in that large datagram

is supported by substantial evidence.

CONCLUSION

We have considered Alacritech’s remaining arguments 

and find them unpersuasive. For the reasons stated above, 

we affirm the Board’s conclusion that the claims at issue 

are unpatentable.

AFFIRMED

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